在javascript中计算最后一个月的日期 [英] Calculate last day of month in javascript

问题描述

如果您在Date.setFullYear中提供0作为dayValue，您将获得上个月的最后一天：

if you provide 0 as the dayValue in Date.setFullYear you get the last day of the previous month:

d = new Date(); d.setFullYear(2008, 11, 0); //  Sun Nov 30 2008

在 mozilla 。这是一个可靠的跨浏览器功能，还是应该看看替代方法？

There is reference to this behaviour at mozilla. Is this a reliable cross-browser feature or should I look at alternative methods?

推荐答案

var month = 0; // January
var d = new Date(2008, month + 1, 0);
alert(d); // last day in January

IE 6: Thu Jan 31 00:00:00 CST 2008
IE 7: Thu Jan 31 00:00:00 CST 2008
IE 8: Beta 2: Thu Jan 31 00:00:00 CST 2008
Opera 8.54: Thu, 31 Jan 2008 00:00:00 GMT-0600
Opera 9.27: Thu, 31 Jan 2008 00:00:00 GMT-0600
Opera 9.60: Thu Jan 31 2008 00:00:00 GMT-0600
Firefox 2.0.0.17: Thu Jan 31 2008 00:00:00 GMT-0600 (Canada Central Standard Time)
Firefox 3.0.3: Thu Jan 31 2008 00:00:00 GMT-0600 (Canada Central Standard Time)
Google Chrome 0.2.149.30: Thu Jan 31 2008 00:00:00 GMT-0600 (Canada Central Standard Time)
Safari for Windows 3.1.2: Thu Jan 31 2008 00:00:00 GMT-0600 (Canada Central Standard Time)

输出差异是由于 toString（）实现中的差异，而不是因为日期不同。

Output differences are due to differences in the toString() implementation, not because the dates are different.

当然，只是因为上面确定的浏览器使用0作为上个月的最后一天并不意味着他们会继续这样做，或者t未列出的帽子浏览器将会这样做，但它有可信度，认为它应该在每个浏览器中都是一样的。

Of course, just because the browsers identified above use 0 as the last day of the previous month does not mean they will continue to do so, or that browsers not listed will do so, but it lends credibility to the belief that it should work the same way in every browser.

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